1. Field of the Invention
The present invention relates to methods and apparatus for use in a wellbore; more particularly the invention relates to methods and apparatus for expanding tubulars in a wellbore and specific applications for the expanded tubulars.
2. Background of the Related Art
The drilling, completion and servicing of hydrocarbon wells requires the use of strings of tubulars of various sizes in a wellbore in order to transport tools, provide a path for drilling and production fluids and to line the wellbore in order to isolate oil bearing formations and provide support to the wellbore. For example, a borehole drilled in the earth is typically lined with casing which is inserted into the well and then cemented in place. As the well is drilled to a greater depth, smaller diameter strings of casing are lowered into the wellbore and attached to the bottom of the previous string of casing. Tubulars of an ever-decreasing diameter are placed into a wellbore in a sequential order, with each subsequent string necessarily being smaller than the one before it. This process of casing and cementing is commonly referred to as xe2x80x9ccompletingxe2x80x9d the well. In each instance, a sufficient amount of space must exist in an annular area formed between the tubulars in order to facilitate the fixing, hanging and/or sealing of one tubular from another or the passage of cement or other fluid through the annulus. Typically, when one tubular is hung in a wellbore, a slip assembly is utilized between the outside of the smaller tubular and the inner surface of the larger tubular therearound. One such assembly includes moveable portions, which are driven up cone-shaped members to affix the smaller tubular to the larger tubular in a wedging relationship.
Many of the above drilling and completion methods are also applicable for water wells. Typically, water wells are shallower than hydrocarbon producing wells, encounter lower formation pressures, and are budgeted for drilled and completed at costs significantly less than hydrocarbon producing wells.
Increasingly, lateral wellbores are created in wells to more fully or effectively access hydrocarbon bearing formations. Lateral wellbores are formed off of a vertical wellbore and are directed outwards through the use of a diverter, like a whipstock. After the lateral wellbores are formed, they are typically lined with a tubular creating a junction between the tubulars lining the vertical and lateral wellbores. The junction must be sealed to maintain an independent flow path in and around the wellbores. While prior art technologies have effectively provided means for forming and lining the lateral wellbore, operational effective and cost effective apparatus and methods for completing these wellbores are scarce or, in some situations, nonexistent. Conceptually, lateral water well boreholes can be drilled and completed, but costs are usually out of a normal budget range designated for typical water wells.
Multiple vertical and/or lateral wellbores are typically drilled into a hydrocarbon producing formation in a producing oil or gas xe2x80x9cfieldxe2x80x9d. Early in the life of the field, fluids are typically produced from all wells. The produced fluid is typically a combination of hydrocarbon and water. As the field matures, the fraction of water in the produced fluid (typically referred to as the xe2x80x9cwater cutxe2x80x9d) increases as the level of the water-hydrocarbon interface within the formation increases, and internal formation pressures decrease. Eventually, it is not commercially feasible to produce high water cut wells, even though other wells within the field are producing fluids with commercially acceptable water cuts. In many cases, high water cut wells are converted from producing wells to xe2x80x9cinjectionxe2x80x9d wells. Another approach is to drill additional wells specifically for injection wells. Since these wells do not produce hydrocarbons, cost of drilling and especially cost of completion is a prime economic consideration. A variety of fluids, or combinations of fluids, are injected into the producing formation through injection wells. This injected fluid sweeps through the permeable producing formation to drive remaining hydrocarbons toward the wellbores of the field""s producing wells. Injected fluids can comprise water, gas, hydrocarbons, surfactants, and a variety of combinations and injection sequences of these and other fluids. This process is broadly referred to as xe2x80x9cenchancedxe2x80x9d recovery.
In producing wells, whether hydrocarbon or water, it is highly desirable to control entry of particulate mater, such as sand, into tubulars within the producing wellbore. Particulates are typically filtered from produced fluids using a variety of screens, slotted liners and other tubular filtering means. These filtering means, which are typically set in other tubulars but which can also be set in uncased or xe2x80x9copenxe2x80x9d well boreholes, are known in the art. Conversely, in enhanced recovery injection wells, it is highly desirable to control entry of particulate mater into the formation since particulates tend to clog formation pore space and pore throats connecting the pore space thereby reducing formation permeability. A reduction in permeability decreases the efficiency of the enhanced recovery operation. Prior art teaches the use of various screens, slotted liners, gravel packs and the like to control movement of particulates in a dynamic wellbore fluid flow. All of these prior art methods result in operational and economic disadvantages as will be discussed in subsequent sections of this disclosure.
Economics also play an important role in the completion of hydrocarbon and water wells. As mentioned previously, formations penetrated by a borehole are hydraulically sealed from each other and from the borehole by cement, which is pumped into the casing-borehole annulus. Any means that can reduce the volume of this annulus reduces the required amount of cement which, in turn, reduces the cost of well completion. The cost of completion is further reduced if a hydraulic seal can be obtained directly between the outer surface of casing and the borehole wall, thereby eliminating the need for cementing. Gravel packs have been used to control inclusion of particulates in injection or water wells, especially when these wells are drilled into unconsolidated formations. Gravel packs are expensive and add significantly to the completion cost of the well. Sand screens have been used to control the flow of particulates, but are prone to collapse, especially when the pressure differential across the sand screen is directed alternately from borehole to formation and then from formation to borehole, as the case in xe2x80x9chuff and puffxe2x80x9d operations known in the art.
There is a need for apparatus and methods to quickly and easily position tubular filtering means in targeted formations within vertical and lateral wellbores. There is also a need for apparatus and methods to quickly and easily expand a tubular in a wellbore to a given diameter. There is a further need for apparatus and methods which position and expand tubular filters in boreholes to filter particulate material from fluid flowing between a formation of interest and the well borehole. There is yet a further need for methods and apparatus for expanding tubulars in a wellbore, which permit one tubular to be expanded into an opening formed in another tubular to create a filter for fluids flowing through the opening. There a further need for methods and apparatus permitting a tubular to be expanded within a well borehole thereby reducing the volume of an annulus formed by the outer surface of the tubular and the borehole wall thereby reducing cement volume required in completing the well. There is still a further need for methods and apparatus permitting a tubular to be expanded into an opening in a larger tubular or well borehole, wherein the expanded tubular will withstand pressures created by fluid injected into the larger tubular or borehole, through the expanded tubular, and into an earth formation penetrated by the borehole. There is yet a further need for methods and apparatus to expand a tubular to directly contact a well borehole wall thereby effectively completing the well without the necessity of cementing the tubular-borehole wall annulus.
U.S. Pat. No. 5,901,789 to Martin Donnelly et al discloses a deformable well screen, wherein the stated design criterion is to filter the flow of fluid from a formation penetrated by a borehole into the borehole. The filter device is expandable and utilizes a variety of relatively delicate filter materials including screens, meshes and even cloth. Physical robustness is provided by encasing the filter material between inner and outer expandable, perforated tubulars. When the device is expanded, the inner and outer tubulars prevent the filter element from being collapsed by pressure exerted by the formation into the borehole. The system is expanded from the xe2x80x9cbottom upxe2x80x9d by axially drawing a sized, conical member through the device. The system can not be expanded from the xe2x80x9ctop downxe2x80x9d. and no other means of axial conveyance are taught. In one embodiment of the device, a gravel pack is used to fill any voids between the borehole wall and the outer expandable perforated tubular. Wiper disks below the sized conical expansion member are used to sweep gravel from the borehole and into the voids. Because the wipers essentially block the borehole, fluid circulation can not be maintained within the borehole below the wipers. This can introduce significant operation and safety problems. The reference does not teach the completion of a well by expanding a solid tubular to form a hydraulic seal with the wall of a wellbore.
The present invention relates to methods and apparatus for expanding tubulars in a wellbore. In one aspect of the invention, an expansion tool with hydraulically actuated, radially expandable members is disposed on a string of coil tubing. The string of coil tubing is inserted into the wellbore from a reel at the surface of the well. In addition to providing transportation for the expansion tool into the wellbore, the coil tubing provides a source of hydraulic fluid from the surface of the well to actuate the expansion tool therebelow. A mud motor disposed on the coil tubing string above the expansion tool provides the expansion tool with rotary power. With the expansion tool lowered into a wellbore to a predetermined location within a tubular therearound, the expansion tool may be actuated and rotated and some portion of the tubular therearound expanded to a larger diameter.
In another aspect of the invention, an apparatus includes an expansion tool, a tractor and a mud motor disposed on a coiled tubing string. The tractor, with radially expandable members actuated by hydraulic fluid from the coiled tubing and rotated by the mud motor, propels the apparatus axially in the wellbore while the expansion tool expands the tubular therearound through radial force and rotation. In use, the apparatus is lowered into the wellbore from the surface of the well to a predetermined depth within a tubular therearound. Thereafter, the tractor is actuated by the mud motor and provides axial movement of the apparatus while the expansion tool rotates and expansion members thereupon are actuated to increase the diameter of a tubular therearound.
In another aspect of the invention, an apparatus is provided having an electric motor, at least one pump and a hydraulic fluid reservoir disposed in a housing with an expansion tool disposed therebelow. The apparatus is run into the well on a wireline which provides support for the weight of the apparatus and electrical power for the components therein. More specifically, the apparatus is lowered into a tubular in a wellbore to a predetermined depth. Thereafter, electric power supplied to the motor operates the pump to provide pressurized fluid to actuate the expansion tool and a shaft extending from the pump provides rotational power to the expansion tool.
In yet another aspect of the invention, the apparatus further includes a tractor run into the well on wireline along with the expansion tool and the housing enclosing the pump reservoir and motor. The electrical motor operates the pump which provides a source of pressurized fluid to the tractor and the expansion tool. Rotational force to the expansion tool and tractor is provided by an output shaft from the electric motor. In use, the tractor imports axial movement to the apparatus in the wellbore while the expansion tool rotates and expandable members thereupon increase the diameter of the tubular therearound.
In still another aspect of the invention, an apparatus includes a housing with two pumps and an electric motor disposed therein. Disposed above the housing is a tractor and disposed below the housing is an expansion tool. The apparatus is run into the wellbore on wireline which provides support for the weight of the apparatus and electrical power for the electric motor. In use, the electric motor provides power to an upper pump which actuates radially expandable members of the tractor thereby imparting axial movement to the apparatus in the wellbore. Additionally, the electric motor provides power to a lower pump which actuates the expansion tool therebelow. Both the expansion tool and tractor rotate to move the assembly axially in the wellbore and expand a longitudinal section of the tubular when desired.
In a further aspect of the invention, a method is provided using the apparatus of the present invention to position and expand tubular filters in boreholes to filter particulate material from fluid flowing between a formation of interest and the well borehole.
In another aspect of the invention, a method is provided for using the apparatus of the present invention to expanding tubulars in a wellbore which permits one tubular to be expanded into an opening formed in another tubular to create a filter for fluids flowing through the opening. A perforation in casing is an example of such an opening.
In yet another aspect of the invention, a method is provided using the apparatus of the present invention to permit a tubular to be expanded within a well borehole thereby reducing the volume of an annulus formed by the outer surface of the tubular and the borehole wall thereby reducing cement volume required in completing the well.
In a further aspect of the invention, a method is provided using the apparatus of the present invention to permit a tubular to be expanded into an opening in a larger tubular or well borehole, wherein the expanded tubular will withstand pressures created by fluid injected into the larger tubular or borehole, through the expanded tubular, and into an earth formation penetrated by the borehole.
In yet another aspect of the invention, a method is provided using the apparatus of the present invention to expand a tubular to directly contact a well borehole wall. This methodology can be used to effectively complete the well without the necessity of cementing the tubular-borehole wall annulus in order to obtain hydraulic isolation of the penetrated formations.
In still another aspect of the invention, a filter apparatus is expanded within the borehole to provide a means for removing particulate material from fluid injected into a formation in an enhanced recovery operation.
In a further aspect of the invention, a method is provided, using the apparatus of the present invention, to expand by rotation a tubular filter in another tubular to effect a substantially sealed junction and thereby provide filtration of injected fluids in a vertical or a lateral wellbore.